وَمَا جَعَلَهُ ٱللَّهُ إِلَّا بُشْرَىٰ وَلِتَطْمَئِنَّ بِهِ قُلُوبُكُمْ ۚ وَمَا ٱلنَّصْرُ إِلَّا مِنْ عِندِ ٱللَّهِ ۚ إِنَّ ٱللَّهَ عَزِيزٌ حَكِيمٌ

The battle of Badr took place under very critical conditions. Only 313 Muslims were pitted against about one thousand well-armed enemies. The Muslims were scantily armed. The enemies had already reached the venue of battle (Badr) and had captured a vantage point and the spring of water. Seeing this, the Muslims were beset by doubts that perhaps they would not be supported by God in the mission for which they had been sacrificing their lives. Had truth been on their side, God would not have helped the enemies on this critical occasion and all the favourable opportunities would have slipped from their grasp and passed on to their enemies. But at that time, Almighty God caused heavy rains to fall in the area of Badr. Muslims made ponds and stored the water. The enemy had deprived Muslims of the water of the land; God then arranged for them to have water from the sky. God furthermore blessed them with an extraordinary favour—that of sleep. Sleep is very necessary for a man to be refreshed, but the conditions in the battlefield are so terrible that it is impossible to have sound sleep. In spite of this, Almighty God blessed them with His special succour; on the eve of the battle, He made it possible for them to have sound sleep. In the night they slept free of all mental pressure and got up in the morning fully refreshed. Out of conditions which were causing Muslims to have misgivings, God created such possibilities that they developed new faith and a sense of self-reliance.

— Source: Tazkirul Quran (Maulana Wahiduddin Khan) via Quran.com (8:10)